I see racers bring Nitrogen Tanks for inflating and seating tires. This seems like a really great idea. My Speedway air tank needs constant filling, and can only seat 1 tire before the pressure drops too much. My question is how large of a tank do I need? I want the lowest weight, and a decent capacity so I only have to refill once once every other month or so Would 20cf be about right?

It costs almost the same to fill a 20 tank as a 120 tank. I had the small bottle & it was a pita. Always empty. My Airgas store gave me full credit on the small bottle for a 120cf bottle. That lasts a couple of race weekends with me using it to run an air wrench & do tires